A projectile may spin rapidly about an axis while the projectile is in flight. The projectile may include an on-board guidance system to modify control surfaces of the projectile in order to steer the projectile precisely along a desired trajectory. The guidance system typically tracks yaw, pitch, and roll of the projectile and modifies the control surfaces accordingly. Traditional techniques used to track high roll rates of the spinning projectile are complicated and expensive to implement. Moreover, one such technique detects phase differences between signals received through multiple separated antennas fixed to a periphery of the projectile and separated sufficiently to generate noticeable phase differences; however, guided projectiles are often too small to accommodate the required antenna separation.